JPH03253272A - Oscillation wave motor - Google Patents

Abstract

PURPOSE:To obtain squareness of an output member of a shaft, etc., with high accuracy and, at the same time, to detect a better position even in the case where an encoder device is provided by providing a plurality of bearing members to the same member, and supporting the output member by those bearing members only so that they are capable of rotation. CONSTITUTION:A housing 2 is rotated to work and finish bearing fit sections 2-b and 2-c and a reference plane 2-a in succession by a cutting tool. According to the constitution, perpendicularity of an axis of the bearing fit sections 2-d and 2-c with the reference plane 2-a can be worked to the extent of 1mum with high accuracy. Two bearings 14 and 15 are loaded to the bearing fit sections 2-d and 2-c of the worked housing 2 with high accuracy, and such a construction as an output shaft 11 is pivoted is made by two loaded bearings 14 and 15. According to the constitution, perpendicularity with high accuracy against the reference plane 2 of a motor can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vibration wave motor that frictionally drives a moving body using progressive vibration waves.

[Prior Art] A proposal regarding the structure of a vibration wave motor using bending vibration of a piezoelectric body has been proposed in Japanese Patent Application Laid-open No. 83-73887.

The above proposal is 1) Small and compact vibration wave motor 2) Vibration wave motor with excellent heat dissipation 3) Highly efficient vibration wave motor 4) Vibration wave motor with easy pressure adjustment It provides:

Since the driving principle of the vibration wave motor is well known, it will not be explained in detail, but will be briefly explained below.

In a vibration wave motor, a piezoelectric element is bonded with adhesive to one side of an elastic body made of metal, for example, formed in an annular shape, and two groups of piezoelectric elements for driving formed on the piezoelectric element have different phases. By applying an alternating current voltage, two standing waves are excited on the elastic body, and a progressive vibration wave, which is a bending vibration, is formed by combining these standing waves.

On the other hand, on the other side of the elastic body, an annular member, for example, is pressurized via a pressure means such as a spring, and the member is moved by friction drive caused by progressive vibration waves formed in the elastic body. or move the elastic body.

A conventional example will be explained with reference to FIG.

2 is a cover of the motor, and 1 is a case. A piezoelectric body 4 is fixed to the elastic body 3, and these act as stators (
vibrating body) 5. The increase in motor temperature due to the heat generated by the stator 5 is caused by the stator 5, cover 2, case 1
It has a structure that conducts and dissipates it.

Reference numeral 8 denotes a rotor constructed by fixing a slider 7 to a ring 6. This rotor 8 is pressed against the stator 5 by the pressing force of a spring 10 with a rubber body 9 in between, and the shaft 11
It is designed to rotate together with the Pressure force is shim 12
After selecting and adjusting the thickness of the snap ring 13
It can be adjusted very easily. The shaft 11 is rotatably supported by bearings 14 and 15 attached to the case 1 and the cover 2, respectively.

FIG. 6 is a diagram showing a state in which an encoder device is attached to a conventional vibration wave motor.

35 is an encoder device, which is fixed to the encoder mounting plate 40 with screws 41, and is connected to the shaft 11 of the vibration wave motor.
is connected to the shaft stepped portion 11-b by a coupling 42.

[Problems to be Solved by the Invention] However, in the conventional example described above, the shaft 11 is supported by two bearings 14 and 15 installed in bearing fitting portions formed in the case 1 and cover 2, which are separate members. As a result, it had the following drawbacks.

1) The two bearings are each made of separate members, and due to fitting errors between case 1 and cover 2,
Since the coaxiality of the bearing portions increases, the center of rotation of the shaft 11 supported by the bearing portions becomes tilted.

Therefore, the parallelism of the opposing surfaces of the rotor 8 fixed to the shaft 11 and the stator 5 fixed to the cover 2 increases. In order to eliminate this drawback, in the conventional example, the parallelism error is attempted to be absorbed by the flexibility of the thin wall portion 3-a of the stator 5 and the support structure of the rotor 8, but this is not always perfect, and If vibration wave motors are characterized by "quick rises and falls", the flexible structure of the rotor 8 and stator 5 may be delayed in following the deflection, or the reaction force may cause unintentional damage. This may cause excessive excitation force to be generated, which may affect the motor and reduce accuracy.

2) When a perpendicularity between the shaft 11 and the mounting surface 2-a of the motor device is required (for example, perpendicularity of 10 μm or less), a motor that can best take advantage of another feature of the vibration wave motor: generating high torque at low speed. The method of use is a direct drive system, but in most cases, the direct drive system requires precision in perpendicularity of the shaft to the driven part. However, in the conventional example, as described above, the shaft 11 and the mounting surface 2-
It is difficult to improve the perpendicularity with a, and there is a drawback that the special characteristics of the vibration wave motor cannot be utilized.

3) As can be seen from the fact that 70% of servo motors have an encoder built into the motor, there is a strong need for a built-in encoder.In particular, if a high-precision, high-resolution encoder is built-in, the characteristics of the encoder do,
Extremely high precision is required for the positional relationship between the rotor section of the encoder and the stator detection section of the encoder, the coaxiality with the shaft 11 on which the rotor of the encoder is attached, and the runout precision, but as described in the drawback 2) above. In the conventional example, it is clearly difficult to achieve high precision.

Further, in the configuration shown in FIG. 6 in which the encoder device 35 is connected by a coupling 42, the motor device including the encoder device 35 becomes large, which hinders miniaturization of the device.

Furthermore, as shown in FIG. 6, since the encoder device 35 is connected with a coupling 42, position detection errors may occur due to misalignment errors caused by the coupling 42, torsional errors due to torsional rigidity lower than that of the shaft 11, and torsional vibrations. was.

The purpose of the present invention is to solve such conventional problems, to obtain extremely high-precision squareness of output members such as shafts, and to obtain good position detection even when an encoder device is attached. Our goal is to provide a vibration wave motor that can.

[Means for Solving the Problem] The gist of the present invention to achieve the object is to solve the problem of progressive tremor! The annular vibrating body in which the III wave is formed is fixed by a supporting and fixing member, and the movable body fixed to the output member is brought into pressure contact with the vibrating body via a pressure means, so that the vibration formed on the vibrating body is In a vibration wave motor that frictionally drives the movable body using progressive vibration waves and receives rotational output from the output member positioned at the center of rotation, a plurality of bearing members that rotatably support the output member are provided in the same member. A vibration wave motor is provided.

[Function] The vibration wave motor having the above configuration has a plurality of bearing members provided on the same member and rotatably supports the output member only by these bearing members, thereby improving the coaxiality and coaxiality of the plurality of bearing members. Achieves high accuracy in the perpendicularity of the output member.

[Embodiment] FIG. 1 is a longitudinal sectional view showing an embodiment of a vibration wave motor according to the present invention.

In FIG. 1, members having the same functions as those of the conventional example shown in FIGS. 5 and 6 are given the same reference numerals, and their explanations will be omitted.

1 is a motor case; 2 is a motor housing; a rotor 8 and a stator 5 are housed in a space covered by the housing 2 and the case 1; A cylindrical portion 2-d is integrally formed in the center of the housing 2, and bearing fitting portions 2-d are integrally and coaxially formed at both ends and outer ends of the cylindrical portion 2-d.
Ball bearings 14 and 15 are attached to the ball bearings 14 and 2-c, and the output shaft 11 can rotate freely through these ball bearings 14 and 15, and can slide in the vertical direction in the figure with respect to the inner ring of the ball bearing. It is pivoted. Further, a stator 5 in which a piezoelectric element 4 is fixed to an elastic body 3 is attached to the housing 2 with screws 21.

The slider 7 is fixed to the ring 6, and a rubber ring 9 is sandwiched between the ring 6 and the support 20 to form a rotor 8.

a preload collar 17 in contact with the inner ring of the lower ball bearing 14;
The spring 10 sandwiched between the pressure bosses 18 is
By applying pressure to the end surface 18-8 of 8 and the end surface 20-a of the support body 20, and tightening each stopper 22, the spring force of the spring 10 causes the bearing 14 to be bent.
At the same time, the rotor 8 is brought into pressure contact with the stator 5.

On the other hand, the bearing 15 has a preload collar 1 fixed to the output shaft 11.
A preload is applied by 6.

That is, the case 1 only has the function of a cover attached to the housing 2, and does not have the function of a bearing for the output shaft 11.

An example of the finishing method for the housing 2 in this embodiment will be explained with reference to FIG. 25 is the chuck of the lathe;
Chuck the cylindrical portion 2-d of the housing 2 and remove the housing 2.
is rotated and the cutting blades 23 and 24 are used to continuously process and finish the bearing fitting portions 2-b and 2-c and the reference surface 2-a.

Thereby, the perpendicularity between the axes of the bearing fitting portions 2-a and 2-b with respect to the reference surface 2-a can be machined with high precision of about 1 μD. Two bearings 14, 1 are installed in the bearing fitting parts 2-d and 2-c of the housing 2, which are finished with high precision.
5 and the output shaft 11 is pivotally supported by the two attached bearings 14 and 15, it is possible to realize an extremely highly accurate perpendicularity with respect to the motor reference plane 2-a.

FIG. 3 shows an example in which an optical encoder device is incorporated into the vibration wave motor shown in FIG.

A chart stand 29 is fixed to the stepped portion 11-a of the output shaft 11. The mounting surface 29-8 of the encoder chart 28 on the chart stand 29 is roughly machined by driving the vibration wave motor A, and the mounting surface 29-a is machined with high precision relative to the output shaft 11. There is. Furthermore, the mounting surface 29-a
An encoder chart 28 is fixed to the.

Mounting surface 2- of encoder fixed side member 25 of housing 2
The bearing fitting surfaces 2-b and 2-c are machined using the same machining method as the example shown in Fig. 2, and the coaxiality and perpendicularity of the bearing fitting surfaces 2-f and 2-f are made with high accuracy. It is processed into.

27 is an index chart, which is fixed to the fixed side member 25; 30 is a mounting base for the light emitting element 31, which is fixed to the fixed side member 25; the light from the light emitting element 31 passes through the chart 28 and the index chart 27; The light then reaches the light receiving element 26 fixed to the fixed side member 25. 33 is
It is an amplification and waveform shaping circuit for the light emitting element 31 and the light receiving element 26, and is fixed to the mounting base 30 with a spacer 32. 34 is an encoder case that protects the optical components and circuit section of the encoder 35. The amplified and waveform-shaped signal is guided to an external motor control circuit (not shown) via a signal line (not shown), and the rotation of the motor is controlled.

In the embodiment of FIG. 3, an encoder 35 is installed on the outside of motor A.
is arranged inside the motor A, and the encoder method is not limited to the method of the embodiment, but may be another optical encoder such as a laser rotary encoder.
A method other than the optical method may also be used.

FIG. 4 shows another embodiment.

In this embodiment, an inner race 11-a is formed directly on the output shaft 11, and the inner bearing 15° is assembled into a shaft-integrated bearing. The shaft-integrated bearing 15° has a configuration in which the inner ring of the bearing is omitted, eliminating precision errors in the inner ring, resulting in even higher precision of the output shaft, and even more accurate vibration than the embodiment shown in Figure 1. Can provide wave motor.

Further, the preload collar 16 of the embodiment shown in FIG. 1 can be omitted in the shaft-integrated bearing at 15 degrees because the preload can be applied by the inner race 11-a. Further, although ball bearings are used in the above embodiments, it may be a sliding bearing, a dynamic pressure bearing, a static pressure bearing, a magnetic bearing, or a combination thereof.

In addition, in each of these examples, the rotation is on the inner ring side,
It is also possible to rotate the outer ring.

Furthermore, the bearing fitting parts 2-b, 2-c and the motor reference surface 2
-a, etc. may be integrally molded when the housing 2 is molded.

[Effects of the Invention] As explained above, according to the present invention, by providing a plurality of bearing members on the same member and pivotally supporting the output member by these bearing members, it is possible to achieve extremely high precision that has not been seen before. It is possible to provide a high-precision vibration wave motor that can achieve perpendicularity of the output shaft and can be sufficiently applied to driven parts that require high precision.

In addition, by achieving high precision of the output member, it is possible to provide a vibration wave motor with a built-in encoder having high precision and high resolution.

Further, by configuring the bearing portions from the same member, it is possible to unitize the bearing portions, which also has the effect of improving ease of assembly.

Furthermore, by assembling the encoder device to the output shaft of the vibration wave motor, the conventional vibration wave motor and encoder device were connected by a coupling, but misalignment errors due to accuracy errors of this coupling can be eliminated, and the coupling The torsional rigidity of the output shaft was lower than that of the output shaft, which caused torsional errors and torsional vibrations, but these have been eliminated.
This enables more accurate position detection and control.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing an embodiment of a vibration wave motor according to the present invention, Fig. 2 is a diagram explaining a method of processing the housing member, and Fig. 3 is an embodiment of a vibration wave motor with an encoder assembled. , FIG. 4 is a longitudinal sectional view showing another embodiment, FIG. 5 is a longitudinal sectional view showing a conventional vibration wave motor, and FIG. 6 is a longitudinal sectional view showing a conventional example in which an encoder is assembled. 1...Motor case 2...Housing 3...
・Elastic body 4...Piezoelectric element 5...Stator 6...Ring 7...Slider
8... Rotor 9... Rubber ring 10...
・Spring 11... Output shaft 12... Spacer 13... Snap ring 14... Bearing 15
... Bearing 16.17 ... Preload collar 1
8... Pressure boss 19, 21.22... Screw 20... Support body 23.24... Cutting blade 25... Fixed side member 26... Light receiving element 27.
...Index chart 28...Chart 29...Chart stand 3
0...Mounting base 31...Light emitting element 32...
・Spacer 33... Encoder circuit 34... Encoder case 35... Encoder device and 4 other people Figure 3 Figure 2 Figure 4 Figure Figure Figure

Claims (1)

[Scope of Claims] 1. An annular vibrating body in which progressive vibration waves are formed is fixed by a supporting and fixing member, and a movable body fixed to an output member is pressurized by a pressurizing means. A vibration wave motor that frictionally drives the movable body by a progressive vibration wave formed in the vibrating body and generates a rotational output from the output member positioned at the center of rotation, the output member being rotatable. A vibration wave motor characterized in that a plurality of supporting bearing members are provided on the same member. 2. The vibration wave motor according to claim 1, wherein the member that supports the plurality of bearing members is a supporting and fixing member that supports the vibrating body. 3. A vibration wave motor according to claim 2, wherein the fixed part side of the rotation detection means is fixed to the fixed member, and the rotation member of the rotation detection means is fixed to the output member. 4. In the vibration wave motor of claim 3, the mounting joint surface of the rotation detecting means on the fixed member of the fixed member and the supporting surface of the fixed member that supports the bearing member of the output member are integrally formed by a cut surface by cutting or by an integral molding method. A vibration wave motor characterized by having a molded surface formed into a molded surface.